The present invention relates to a clip-on optic assembly, and more particularly to such an assembly which is capable of being clipped in situ onto a previously implanted artificial intraocular lens to change the optical characteristics thereof without having to remove the implanted lens from the eye, by insertion of the assembly through an incision into the eye and clipping it onto the implanted lens.
A recent innovation in the intraocular lens field is a new system intraocular lens whose lens body has a small central "high-minus" lens portion of approximately 2 mm diameter, surrounded by a peripherally extending, much more "positive" lens portion (J Cataract Refrac Surg, 14:421-430, July, 1988).
This new system intraocular lens is intended for patients with severe macula degeneration, as it allows the patient to see normally, by viewing through the peripherally extending portion, objects that are at a distance. On the other hand, for close vision, e.g. reading, eyeglasses having a compensating "plus" lens are worn by the user, the combination of the "plus" lens of the eyeglasses and the "high-minus" central lens portion of the intraocular lens together forming a structure of optical characteristics resembling those of a telescope for producing a magnified image on the retina.
However, patients who already have an implanted intraocular lens can only avail themselves of this new system by removing the existing implanted lens and replacing it with one having such a "high-minus" central portion. Due to tissue growth around the haptics or other position fixation means used to maintain the already implanted lens in the eye, as well as adhesion of eye tissue to other portions of the implant, especially where that lens has been implanted for an extended period of time, its removal and replacement involves relatively major and complex surgery and the risk of loss of vision.
U.S. Pat. No. 4,769,035, issued Sep. 6, 1988, to Kelman shows an artifical lens formed of a predetermined shape optic having a concave posterior surface corresponding to the anterior surface of the natural lens when the latter is in its flattest condition, and opposed haptics, adapted to seat in the surrounding tissue of the eye, to position the artificial lens, upon insertion through an incision into the eye, with its posterior surface seated directly against the anterior surface of the natural lens which remains in place and is not removed from the eye. The artificial lens cooperates with the natural lens for correcting conditions such as myopia and hyperopia.
U.S. Pat. No. 4,585,456, issued Apr. 29, 1986, to Blackmore also shows an artificial lens having haptics or the like, adapted to seat in the surrounding tissue of the eye, for locating the conforming posterior side of the artificial lens against the natural lens for correcting an eyesight condition.
It would be desirable to provide the benefits of the aforesaid new system intraocular lens having a "high-minus" central lens portion surrounded by a more "positive" peripheral lens portion, or other optical characteristic modifying benefits, to a patient already having an implanted intraocular lens, without subjecting the patient to removal of the latter and its replacement by such a new system intraocular lens, or to the risks of major or complex surgery.